Liver exposure to xenobiotics: the aging factor and potentials for functional foods

Natural Compounds as Integrative Therapy for Liver Protection against Inflammatory and Carcinogenic Mechanisms: From Induction to Molecular Biology Advancement

The liver is exposed to several harmful substances that bear the potential to cause excessive liver damage ranging from hepatitis and non-alcoholic fatty liver disease to extreme cases of liver cirrhosis and hepatocellular carcinoma. Liver ailments have been effectively treated from very old times with Chinese medicinal herbal formulations and later also applied by controlled trials in Japan. However, these traditional practices have been hardly well characterized in the past till in the last decades when more qualified studies have been carried out. Modern advances have given rise to specific molecular targets which are specifically good candidates for affecting the intricate mechanisms that play a role at the molecular level. These therapeutic regimens that mainly affect the progression of the disease by inhibiting the gene expression levels or by blocking essential molecular pathways or releasing cytokines may prove to play a vital role in minimizing the tissue damage. This review, therefore, tries to throw light upon the variation in the therapies for the treatment of benign and malignant liver disease from ancient times to the current date. Nonetheless, clinical research exploring the effectiveness of herbal medicines in the treatment of benign chronic liver diseases as well as prevention and treatment of HCC is still warranted.

Canalicular Mrp2 localization is reversibly regulated by the intracellular redox status

Oxidative stress is known to be a common feature of cholestatic syndrome. We have described the internalization of multidrug resistance-associated protein 2 (Mrp2), a biliary transporter involved in bile salt-independent bile flow, under acute oxidative stress, and a series of signaling pathways finally leading to the activation of novel protein kinase C were involved in this mechanism; however, it has been unclear whether the internalized Mrp2 localization was relocalized to the canalicular membrane when the intracellular redox status was recovered from oxidative stress. In this study, we demonstrated that decreased canalicular expression of Mrp2 induced by tertiary-butyl hydroperoxide (t-BHP) was recovered to the canalicular membrane by the replenishment of GSH by GSH-ethyl ester, a cell-permeable form of GSH. Moreover, pretreatment of isolated rat hepatocytes with colchicine and PKA inhibitor did not affect the t-BHP-induced Mrp2 internalization process but did prevent the Mrp2 recycling process induced by GSH replenishment. Moreover, intracellular cAMP concentration similarly changed with the change of intracellular GSH content. Taken together, our data clearly indicate that the redox-sensitive balance of PKA/PKC activation regulates the reversible Mrp2 localization in two different pathways, the microtubule-independent internalization pathway and -dependent recycling pathway of Mrp2.